Constant-level balloon



Oct. 3, 1950 l.. w. lsoM CONSTANT' LEVEL BALLOON Filed July 3l, 1948 W .nn Rmm mQO Nw r Vy ,A

Patented Oct. 3, 1950 CONSTANT-LEVEL ALLooN Langley W. Isom,Belmont, Mass., assigner' to Dewey and Almy Chemical Company,-Cam bridge, Mass., a corporation of Massachusetts Application July 31, 1948, Serial No. 41,765

` 4 Claims. (Cl. 244-24) This invention relates to a constant-level balloon having an elastic envelope.

Aside from important military uses, certainv meteorological investigations require balloons or other devices that will stay at substantially constant altitudes over relatively long periods of time, at heights rendering captive balloons or kites unpractioal. Such balloons also must often be free-dying in order that motions of air masses can be followed.

A balloon consisting of a sealed 'elastic envelope filled with a gas that is less dense than air will rise until the envelope bursts. With such balloons the difference between the interior and the exterior pressures is extremely small and substantially constant. When such a balloon rises, the surrounding atmospheric pressure decreases, causing the envelope to expand, for the interior pressure also decreases resulting in a corresponding increase in volume. The net result is a substantially constant lifting force, independentA of altitude. The balloon rises until the envelope is expanded beyond its elastic limit, when it bursts.

A balloon consisting of a non-elastic envelope with an opening r other means of discharging gas as the atmospheric pressure decreases dissipates its lifting force as the balloon rises, due to the discharge of its gas. Such'a balloon attains an altitude where the lifting force balances the load carried by the balloon.

To arrest the ascent of a balloon with an elastic envelope, gas must be removed as the balloon approaches the proper altitude. Balloons with elastic envelopes can be made considerably lighter and cheaper than can balloons of the same size with non-elastic envelopes. It is, therefore, desirable to have an elastic balloon that willV maintain a constantv altitude.

It is the object of my invention to produce a free-flying elastic balloon that will rise to and at a practically constant altitude over a relatively long period of time without unduly loading the balloon with heavy equipment.

My invention can best be explained by referring to the drawing which is a vertical section through the lowermost portions of the' balloon showing, in vertical section, means for releasing gas therefrom to maintain the balloon at constant altitude. Theballoon consists of an elastic envelope I having a neck Ia. The neck Iais fitted around a cylindrical tube 6 which projects upward just beyond the joinder of the neck la with the main part of the envelope I. lThe tube 6 projects beyond the lower end of the neck Ia a suflicient distance to function as herebelow described. 1 The lower threaded portion of the rod, the function v tube t is of larger internal diameter at the lower end than it is at the upper end and is provided with a planar annular transverse surface 6a at the junction of the upper narrow cylindrical section with the lower wider cylindrical section.

This annular surface 6a provides a valve seat,

whose function will become evident herebelow. The seizing 5 secures the tube 6 in the neckY la. Mounted concentrically within tube 6 is tube l, secured rigidly in place by the brackets 9 which are fastened to the exterior wall of tube l and the interior wall of tube 6. Tube I extends upward into the envelope I beyond the top of tube 6. The upper end of tube l is inserted into the neck 2a of a flexible envelope 2, which envelope 2 is completely surrounded by an inelastic fabric envelope 3. Both of these envelopes are secured to' tube I by seizing E in the saine manner that the envelope I is secured to the upper end of the tube 6. These envelopes 2 and 3 are within the envelope I. The lower end of tube l is coplanar with the annular suri'acea. or tube 6.

Positioned axially in the center of tube l, by means of bracket Ill, is a rod 8, threaded on its lower end. The rod 8 extends below the lower end of the interior tube l.

Fitted around the rod B is a sleeve l2 and a f disc II which is secured to the lower end of the disc II is free tovslide along and on the rod B.

The disc I l acts as a valve plate, closing the tubesv 6 and I when in simultaneous contact with the lower end of tube 'I and the annular surface 6d. The sleeve I2 serves to prevent wobbling of the disc I I and also more effectively seals the interior of tube I from the atmosphere than would be accomplished merely by a hole through the disc II. The inside surface of the disc lI may be covered with a compressible material, as rubber, to render more tight the closure of the tubes 6 and 'I.

Acting upwardly against the disc II is a coil spring I3 which reacts against the washer I5 and al Wingnut I4. 'Ihe Wingnut is threaded on the of saidrod being solely to provide means of yieldingly holding the disc l I against the endof tube 'I and the annular surface Ba. of tube 6.

The Wingnut I4 provides'means for varying the force with which the disc II is urged against the end of tube and the annular surface 6a.

The lower, wider portion of tube 6 serves to II spring I3, Wingnut I4, and the lower end of 3 the rod 8, and to protect the adjustment of the pressure of the spring I3 against the disc II.

Ihe separate envelopes I and 2 are iilled through the tubes II and I6, respectively, which enter the tubes 6 and l, respectively, radially so that the bores of the tubes I'I and I6 are solely in communication with the interiors of tubes 6 and l, respectively. Tube I6 passes through the Wall of tube 6 and enters tube I and is secured tightly to both tubes to prevent any leakage of gas through said walls of the tubes 6 and 1. Tube II enters through the Wall of tube 6 and is sealed thereto. Tapered plugs Ilia and I 'Ia t the interiors of tubes I6 and Il, respectively, and provide means for closing said tubes.

In operation, the compression of the spring I3 is adjusted by means of the wingnut I4 tov exert just suflicient pressure against the disc I I to close the tubes 6 and l against the internal pressure of the envelope I. lThe envelope I is then filled with a suitable gas, as hydrogen or helium, by connecting a hose to the end of tube Il, which hose is also connected to a source of gas. When the envelope I is filled to thek proper diameter,

lthe hose is removed and the stopper Ila is in- L Serted into the end of the tube I'I.

Then through the tube I6 is` introduced into the envelope 2 l such a quantity of gas (air will do) as will fill the envelope 2 to the extent allowed by theA restraining non-elastic envelope 3 at the altitude desired for initiating the escape ofgasefrolm, the envelope I. With this amount of air in the envelope 2, the tube I6 is plugged with. the. Stopper 'Bai It can be readily seen that untill the envelope 2 is rully distended by the expansion of the air therein, the pressure of this air is the same as the pressure of the gas within the outer en vellope IL, both` pressures.4 being slightly higher than the surrounding atmospheric pressure.

balloon ascends, the diierence lbetween the atmospheric pressure andthe internal pressuresl is constant, and the valvepremains closed bythe pressure exerted by the spring I3 against the d isc II. Buty when the envelope 2` has expanded to its full limit as determined by the non-elastic envelope 3, the pressure within the envelope 2 relative tothe pressure within the outer envelope I, and to the atmospheric pressure,y increases. the inner surface of the disc II over the area closing the lower end of tube '1, causes the disc II to remove from contact with the end of tube l' and simultaneously break contact with the annular surface 6a of the tube 6. Gas then escapes from the envelope I and also from the envelope 2. The rate of ascent is, therefore, decreased. The pressure within the envelope 2 also decreases, but as the valve closes and the balloon continues to rise to regions of lower atmospheric pressure, the relative pressure in the envelope 2 continues to increase and reopens the valve by again forcing the disc II away from the tube 1 and away from the annular surface 6a. rllhis process results in continual discharge of gas from theenvelope I and consequently in a continual decrease in the rate of ascent. It continues until sufficient gas has escaped from the envelope I to arrest completely the ascent of4 the balloon. The valve then closes permanently, for with no further ascent and corresponding decrease in atmospheric pressure the relative pressure Within the envelope 2 can no longer increase.

When ascent is arrested completely in this This pressure, acting against manner, the lifting force exactly balances the load and the balloon remains at a constant altitude, except for the effect of diffusion of the gas through the envelope which can be compensated for by employing means for dropping ballast from the balloon.

It is an essential feature of my invention that the gas Within the non-.elastic envelope be allowed to escape when the valve is open, simulf. taneously with the escape of gas from the main balloon. vThis permits the valve to close again at a higher altitude than Where it opened, by virtue of the decreased pressure within the nonelastic envelope after the escape of gas therefrom. Should the interior of the non-elastic envelope be sealed from the atmosphere when the valve is open, as where a piston within the tube l actuates the valve, the valve would open at some altitude determined by the amount of gas within the non-elastic envelope and the pressure exerted in opposition by the spring. The valve would not close again until the balloon dropped below the altitude at which it opened, for it is actuated solely by the relative pressure within the non-elastic envelope.

It is understood that the above description of my invention is but one of several ways of putting it into practice. The description places the nonelastic gas-containing envelope in the interior of the large main envelope, as thisis a convenient and practical place for it. But it can be readily seen that this non-elastic envelope, with the sur rounded. bladder, couldvjust as well be placed exterior to the main envelope without affecting the r performance of my invention. Conduit means would then be necessary te conduct the pressure in the non-elastic envelope to onek of the concentric tubes shown in the drawing as 6 or 1. The other tube, of course, would be in communica- I; tion with the interior of the main balloon.

I claim asmy invention:

1. A` constant-level, free-dying balloon comprising an elastic envelope which is free to expand without restraint and is adapted to contain a lifting gas, an independent non-elastic envelope adaptedy to contain gas, and a valve including a single valve member operative to permit the passage of gas from the elastic envelope and from the non-.elastic envelope to the atmosphere, said member being actuated. solely bythe pressure in the non-elastic envelope.

2. A constant-level, free-flying balloon comprising anv outer elastic envelope which is free to expand without restraint and is adapted to contain a lifting gas, an inner non-elastic envelope adapted to contain gas, a valve including a diaphragm operative toy permit the passage of gas from the outer and from the inner envelopes to the atmosphere, said diaphragm being actuated; solely, by the pressure inthe inner envelope, and conduit means of applying the, pressure in the innerv envelope to actuate the diaphragm.

3. In a constant-level, free-flying balloon comprising an elastic envelope which is free to expand without restraint and is adapted to contain a lifting gas, the combination of an independent, non-elasticv envelope adapted to contain gas, a valve adapted to permit the escape of gas from both o` the envelopes, conduit means of applying thepressure within the independent nonelastic envelope to the valve to actuate the valve to permit the escape of gas from both o1 the envelopes to the atmosphere, and yielding means ofY opposing the force exerted by the pressure within the independent non-elastic envelope.

5 Y 4. In a balloon comprising an elastic envelope 1 REFERENCES CITED which is free to expandwithout restraint and is- The following references are of record in the adapted to contain a lifting gas and an interior, me of this patent: non-elastic envelope adapted to containV gas, a

Valve comprising two concentric tubes, one in 5 UNITED STATES PATENTS communication with the interior of the outer Number Name Date elastic envelope, and the other in communcabn 1,729,516 Naatz Sept. 24, 1929 with the interior of the non-elastic envelope, a 1,926,059 Sutton sept-, 12J 1933 disc adapted to close the outer ends of both tubes, 2,057,194 Kagi c Oct. 13, 1936 and yielding means to hold the disc against the 10 outer ends of the tubes, the outer side of the FOREIGN PATENTS disc being in communication with the atmos- Number Country Date ph'ere, 864,950 France Feb. 10, 1941 LANGLEY W. ISOM. 

